This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application No. 2002-003526 filed in JAPAN on Jan. 10, 2002, which is herein incorporated by reference.
The present invention relates to a multi-piece solid golf ball. More particularly, it relates to a multi-piece solid golf ball, which is superior in flight distance, spin performance, shot feel and scuff resistance.
Amateur golfers generally regard flight distance as most important factor for golf balls and use a solid golf ball having good rebound characteristics and little spin amount, such as a two-piece golf ball, by choice. On the other hand, professional golfers and high level-amateur golfers generally regard controllability as most important factor for golf balls, and regard soft and good shot feel and flight performance as the next important factor for golf balls. Therefore they have mainly used thread wound golf balls, which have good controllability and soft and good shot feel. However, since the thread wound golf ball has a structure easily putting spin thereon, there has been a problem that the spin amount is large when hit by any type of golf club, which reduces the flight distance. In order to solve the problem, many solid golf balls having good shot feel and excellent flight performance while maintaining good controllability have been proposed in Japanese Patent Kokai Publication Nos. 332247/1996, 313643/1997, 151320/1999 and the like.
Japanese Patent Kokai Publication No. 332247/1996 suggests a three-piece solid golf ball comprising a core having a two-layered structure of an inner core and outer core, and a cover. The inner core has a diameter of 25 to 37 mm, a center hardness in JIS-C hardness of 60 to 85 and a hardness difference in JIS-C hardness from the center point to the surface of the inner core of not more than 4, the outer core has a surface hardness in JIS-C hardness of 75 to 90, and the cover has a flexural modulus of 1,200 to 3,600 kg/cm2.
Japanese Patent Kokai Publication No. 313643/1997 suggests a three-piece solid golf ball that an intermediate layer formed from thermoplastic resin is placed between a core and a cover. The core has a center hardness in JIS-C hardness of not more than 75, a surface hardness in JIS-C hardness of not more than 85, the surface hardness is higher than the center hardness by 5 to 25, a hardness of the intermediate layer is higher than the surface hardness of the core by less than 10, and a hardness of the cover is higher than that of the intermediate layer.
Japanese Patent Publication No. 151320/1999 suggests a three-piece solid golf ball comprising a core having a two-layered structure of an inner core and outer core, and a cover. The inner core has a diameter of 15 to 22 mm and a Shore D hardness of 40 to 70, the outer core has a hardness in JIS-C hardness of 40 to 75, the inner and outer core are formed from rubber composition, and the cover has a thickness of 0.5 to 3 mm.
However, in the golf balls, there has been a problem that the spin amount is large, which reduces the flight distance, when hit by a driver to middle iron club such that sufficient flight distance is required. In addition, in order to improve the flight distance, the shot feel is hard or heavy, which is not sufficiently obtained.
A main object of the present invention is to provide a multi-piece solid golf ball, which is superior in flight distance, spin performance, shot feel and scuff resistance.
According to the present invention, the object described above has been accomplished by providing a multi-piece solid golf ball comprising a center, an intermediate layer and a cover, using polyurethane-based thermoplastic elastomer for the cover, and adjusting a diameter and central point hardness of the center, a surface hardness of the intermediate layer and a thickness and hardness of the cover to specified ranges, thereby providing a multi-piece solid golf ball, which is superior in flight distance, spin performance, shot feel and scuff resistance.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.